Ordnance firing system

ABSTRACT

An ordnance system of the present invention may include or feature any one or more of: a control unit, one or more effectors (detonators, initiators, shaped charges and the like), and a two-, three- or four-wire communication bus between the control unit and the effectors; an addressable system in which all the effectors can be connected to the same communication bus and the control unit can issue coded signals on the bus addressed to a specific effector; inductive coupling between the effectors and the communication bus; and a multi-voltage level communication system in which communication signals are carried at a first voltage and arming signals are provided at a second, higher voltage. Other features may include two-way communication between effectors and the control unit and the de-centralization of firing control so that the control unit does not have exclusive control over whether the effectors function. As a result, the individual effectors possess decision-making ability and, for purposes of this invention, may be referred to as “intelligent” effectors. To participate in the decision-making process, effectors of this invention may be equipped with sensors or other diagnostic circuitry whose condition is checked for satisfactory output before functioning is permitted to occur.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a division of U.S. application Ser. No.09/810,089, filed Mar. 16, 2001, which claims benefit of U.S.provisional application No. 60/190,458, filed Mar. 17, 2000.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to the initiation of explosive andpyrotechnic devices in aerospace and aeronautical devices and automotivevehicles.

[0004] 2. Related Art

[0005] Explosive and pyrotechnic devices such as explosive bolts, boltcutters, separation fairings, actuators, engine igniters, etc., are usedin aeronautical and aerospace applications to perform various functionssuch as the separation of one structure from another, the release of astructure from a stowed position to a deployed position, etc. They arealso used in the safety systems of land vehicles such as automobiles,for the deployment of air bags. Such devices are typically coupled toelectrically operated initiators which, in response to suitableelectrical signals, initiate the devices. The initiation signals areprovided by electronic control devices for controlling and coordinatingthe initiation of a plurality of initiators connected thereto. Thecombination of a control unit, a plurality of initiators and anelectrical communication system through which signals are sent from thecontroller to the initiators is referred to herein as an “ordnancefiring system”.

[0006] In the prior art of aeronautical and aerospace devices such asmissiles, satellites, launch vehicles, etc., and of land vehicle safetysystems, the initiators in the ordnance firing systems that control thevarious explosive or pyrotechnic effectors (hereinafter referred tocollectively as “reactive effectors”) typically comprise a hotbridgewire initiating element and an initiating charge of explosive orpyrotechnic material which is sensitive to the initiating element. Inorder to stimulate the hot bridgewire initiating element to releasesufficient energy to ignite the ignition charge, a large amount ofelectrical energy (relative to what is generally required for most otherfunctions on such devices) is required. For example, the firing of a hotbridgewire initiator typically requires a draw of ten amps from a28-volt source for a period of about 0.1 second. Since there are oftennumerous effectors on a given device, the total energy requirement forinitiation of the effectors far exceeds the energy requirement foroperation of the circuitry that controls the device. For this reason,prior art ordnance firing systems typically include a dedicated highpower energy source such as a thermal or chemical battery, for thepurpose of providing sufficient energy to fire the hot bridgewires. Theneed in aerospace and aeronautical devices to provide such batteries,which are large and heavy, has been viewed as an unavoidable butsignificant burden. The batteries occupy space which could go to other,more useful components of the device or to increased payload capacityand, for airborne devices, they also increase the fuel consumption ofthe device at all times during flight.

[0007] Another feature of prior art ordnance firing systems is that allcontrol functions affecting whether the effectors will function residein a control system, from which command signals are forwarded to theeffectors on dedicated wires.

[0008] U.S. Pat. No. 4,708,060 to Bickes, Jr. et al, dated Nov. 24, 1987and entitled “Semiconductor Bridge (SCB) Igniter”, discloses SCB igniterelements, which are described as comprising an electrical semiconductormaterial disposed on a non-conductive substrate. The semiconductormaterial may be, e.g., a layer of n-type silicon that has been dopedwith phosphorus. As indicated in this Patent, other semiconductormaterials and dopants can be used with similar effect. The resistivityof the doped material varies with the dopant level, as iswell-understood in the art. Typically, the semiconductor material isdisposed on the non-conductive substrate by a chemical vapor depositionprocess by which the thickness of the material can be preciselycontrolled. The surface of the non-conductive substrate is usuallymasked during the deposition process so that the layer of semiconductormaterial is rendered in an hourglass shape, i.e., it forms tworelatively large pads joined together by a small bridge. Two pads ofconductive material are then disposed upon the large pads of thesemiconductor material and are separated by the bridge of semiconductormaterial between them. The resistivity of the semiconductor material andthe dimensions of the semiconductor bridge between the conductive padsdetermines the effective resistance that the semiconductor bridgeprovides between the conductive pads. The Patent teaches a preferencefor SCBs of low resistance, e.g., no larger than 10 ohms, for safetyreasons, i.e., in case the SCB is used with an electrostatic sensitiveignition charge (see column 7, lines 44-50) and for a reduction inresistivity with an increase in SCB size (see column 7, lines 53-55).The firing data provided pertain to high amperage (e.g., 10 amps andhigher), short duration electrical initiation signals of less than 100microseconds duration (see column 5, line 62 through column 6, line 3).The comparative data of Table 2 are difficult to interpret because SCB1and SCB2 differ not only in resistance but also in thickness (2micrometers vs. 4 micrometers).

[0009] U.S. Pat. No. 5,831,203 to Ewick, dated Nov. 3, 1998, discloses ahigh impedance semiconductor bridge detonator which illustrates, interalia, that a SCB initiator element may be manufactured on anon-electrically conducting substrate using photolithographic masking,chemical vapor deposition, etc.

[0010] U.S. Pat. No. 4,976,200 to Benson et al, dated Dec. 11, 1990,discloses titanium bridge igniters.

[0011] U.S. Pat. No. 5,085,146 to Baginski, dated Feb. 4, 1992,discloses a planar, multi-layer low-energy initiation element.

SUMMARY OF THE INVENTION

[0012] This invention pertains to an aerospace device comprising aplurality of reactive effectors and, in particular, to the improvementcomprising a plurality of initiators comprising planar, low-energyinitiation elements operatively associated with the effectors forinitiating the same.

[0013] According to one aspect of the invention, the device may comprisea low-energy power source connected to the initiators to provide powerfor arming the initiators.

[0014] According to another aspect of the invention, the device mayfurther comprise a firing control system circuitry connected to theinitiators for controlling the firing of the plurality of initiators,and a low-energy power source for arming the initiators. Optionally,there may be a common communication bus connecting the initiators to thecontrol circuitry.

[0015] In particular embodiments, the device may comprise a missile orlaunch vehicle. Any such device may comprise effectors selected from thegroup consisting of exploding bolts, bolt cutters, motor igniters,release fairings and destruct charges.

[0016] This invention also pertains to an aerospace device comprising aplurality of reactive effectors and, in particular, to the improvementcomprising a plurality of initiators associated with the effectors, afiring control system in communication with the initiators, and at leastone sensor, on the device, for sensing a condition precedent to armingor firing at least one initiator, wherein at least one initiator is incommunication with the sensor and that is responsive to the sensor andto the firing circuitry for initiating its associated effector uponreceipt of proper signals from both the firing circuitry and the sensor.

[0017] Optionally, the device may comprise a common bus through whichthe initiators are linked to the firing circuitry. The sensor may beconnected to the bus or to the initiator responsive to it.

[0018] At least one initiator may be programmed to self-arm or initiatebased on a signal received from the sensor.

[0019] This invention also provides a method for firing an initiator fora reactive effector in an aerospace device or land vehicle comprising atleast one sensor for a condition precedent to firing the initiator. Themethod comprises taking a time-phased reading of the sensor andcomparing the reading to a predetermined temporal profile, and firingthe initiator when the reading correlates to the predetermined profile.

[0020] Another aspect of this invention relates to a land vehiclecomprising a plurality of reactive effectors and, in particular, to theimprovement comprising initiators comprising planar, low-energyinitiation elements for initiating the effectors.

[0021] According to one aspect of the invention, the vehicle maycomprise a low-energy power source connected to the initiators toprovide power for arming the initiators.

[0022] Optionally, the vehicle may further comprise a firing controlsystem circuitry connected to the initiators for controlling the firingof the plurality of initiators for the effectors, and a low-energy powersource for arming the initiators. There may be a common communicationbus connecting the initiators to the control circuitry. Optionally, theeffectors may comprise air bag inflators.

[0023] This invention also pertains to a land vehicle comprising aplurality of reactive effectors and, in particular, to the improvementcomprising a plurality of initiators associated with the effectors, afiring control system in communication with the initiators, and at leastone sensor, on the device, for sensing a condition precedent to armingor firing at least one initiator, wherein at least one initiator is incommunication with the sensor and that is responsive to the sensor andto the firing circuitry for initiating its associated effector uponreceipt of proper signals from both the firing circuitry and the sensor.

[0024] In various embodiments, there may be a common bus through whichthe initiators are linked to the firing circuitry; the sensor may beconnected to the bus; the sensor may be connected to the initiatorresponsive to it; and/or at least one initiator may be programmed toself-arm or initiate based on a signal received from the sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1A is a schematic block diagram of an integrated ordnancefiring system for a missile in accordance with one embodiment of thepresent invention;

[0026]FIG. 1B is a schematic cross-sectional view of a SCB initiator foruse in an aerospace ordnance firing system according to a particularembodiment of the present invention;

[0027]FIG. 1C is a block diagram of an embodiment of an ordnance firingcontrol system according to this invention, which draws power from othercircuitry;

[0028]FIG. 2 is a partial schematic block diagram of an initiator inconnection with a particular embodiment of the invention;

[0029]FIG. 3 is a graph illustrating the time-phased arming of aninitiator in accordance with another embodiment of the invention;

[0030]FIG. 4 is a schematic block diagram of an initiator in accordancewith yet another embodiment of the invention;

[0031]FIG. 5 is a schematic block diagram of an initiator in accordancewith yet another embodiment of the invention; and

[0032]FIG. 6 is a schematic block diagram of a prior art ordnance firingsystem for a missile.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF

[0033] The present invention relates to an ordnance firing system for anaerospace device or a land vehicle comprising a plurality of reactiveeffectors. In one embodiment, the system comprises firing control systemcircuitry for controlling the firing of a plurality of initiators, aplurality of initiators comprising planar low-energy initiation elementsconnected to the firing control system circuitry, a low-energy powersource for arming the initiators and a low-energy power source forpowering the control circuitry.

[0034] In another embodiment, the invention relates to an ordnancefiring system for an aerospace device or a land vehicle comprising aplurality of reactive effectors and a firing control system forcontrolling the firing of a plurality of initiators. In this embodiment,the firing control system comprises a low-energy power source and aninput port for receiving low-energy power for arming the initiators andfor powering the firing control system and for receiving firing controlsignals. There is also a plurality of initiators comprising planar,low-energy initiation elements connected to the firing controlcircuitry.

[0035] Optionally, a system according to this invention may comprise acommon communication bus connecting the initiators to the controlcircuitry.

[0036] An ordnance firing system in accordance with the presentinvention may be utilized on numerous kinds of aeronautical andaerospace devices such as tactical missiles, cruise missiles,surface-to-air missiles, launch vehicles, satellites, etc. (as usedherein, the term “aerospace devices” is meant to include aeronauticaldevices). In such devices, the ordnance system is used to initiate thefunction of various explosive or pyrotechnic effectors such as explodingbolts, bolt cutters, frangible joints, actuators, penetration charges,fragmentation charges, gas generators, inflators, motor igniters,through bulkhead initiators, explosive transfer lines, separationdevices, destruct charges, pyrotechnically actuated valves, etc.,referred to collectively herein as “reactive effectors” to include bothexplosive and pyrotechnic effectors. The ordnance firing system of thisinvention can also be used in land vehicles that utilize reactiveeffectors, e.g., in air bag deployment systems.

[0037] One feature of the present invention is that instead of hotbridgewire initiators, an ordnance firing system in accordance with thisinvention employs initiators that comprise planar, low-power initiationelements, e.g., semiconductor bridge (“SCB”) initiators, tungsten bridgeinitiators as described, e.g., in U.S. Pat. No. 4,976,200, which ishereby incorporated herein by reference, or the type of planar,low-energy initiation element disclosed in U.S. Pat. No. 5,085,146,which is hereby incorporated herein by reference. As a result, the powerrequirement for arming and firing the initiators, and therefore forcausing the effectors to function, is enormously reduced relative toprior art ordnance systems. This is because a planar, low-energyinitiator typically requires only one-tenth the amount of energy tofunction than would be required by a hot bridgewire of comparablereliability and safety. Other prior art initiation elements, e.g.,exploding bridgewires, exploding foil initiators, etc., require evenmore energy than hot bridgewires. Accordingly, where prior art ordnancefiring systems require hundreds of watts of power or more, acorresponding system based on planar, low-energy initiation elements inaccordance with this invention requires only tens of watts or less. Thismeans that an integrated ordnance system according to this invention maybe configured differently from prior art ordnance firing systems. Onedifference is that an ordnance firing system according to this inventiondoes not require a large power source for firing the initiators. Where adedicated power source is provided, a much smaller power source can beused or, in some embodiments, the need for a power source dedicatedsolely to firing the initiators may be eliminated completely.Alternatively, the initiators may optionally contain storage means, suchas a firing capacitor, for storing sufficient energy to fire theinitiation element. Due to the small energy requirement of theinitiation element, the storage means is small enough to incorporateinto the initiator. Typically, the firing capacitor need only provideabout 5 millijoules to provide twice the energy requirements of theplanar initiation element, which typically consumes less than 3millijoules upon firing. In addition, it is possible to charge thefiring capacitor without requiring a large amount of energy, so theinitiator control circuitry can have a relatively high impedance, asdiscussed further below. In fact, the storage capacitor may be chargedfrom power received from the power source provided to enable the controlcircuitry to function. As a result, an enormous savings is seen withrespect to the cost, weight, physical volume and fuel consumption of theordnance firing system for the aerospace device.

[0038] If a hot bridgewire or other device known in the prior art foruse in aerospace or land vehicle ordnance initiation systems (explodingbridgewire, exploding foil, etc.) were designed to function at thelow-energy level of the planar initiators used in accordance with thisinvention, it would not offer the combined safety and reliabilityrequired in the aerospace and automotive safety industries. Theapplicants have found, however, that initiators that meet generallyaccepted safety specifications and which function reliably in aerospacedevices and land vehicles, and which require significantly less energyupon firing than prior art devices can be achieved by the use of planar,low-energy initiation elements as described herein. One crucialdifference is that planar initiation elements are typically formed onheat-dispersing material such as a silicon or sapphire substrate whichacts as a heat sink for the initiation element. The initiation elementcan therefore tolerate a significant degree of stray energy within theno-fire limit, whereas a bridgewire or other prior art element typicallycannot dissipate heat as quickly and therefore is more vulnerable tostray currents. A planar initiation element can therefore maintain asatisfactory no-fire characteristic (e.g., 1 ampere, 1 watt) even whenit is designed to fire with low energy, e.g., less than 3 millijoules.

[0039] In addition to a reduction in the power requirement and thepotential elimination of the need for a dedicated power source, thepresent invention allows for significant reduction in size of theinitiator, even though a storage means (firing capacitor) for firing theinitiator is disposed within the initiator housing. Part of the reasonfor this size reduction is that the low-energy initiation element doesnot require associated circuitry with the power handling capacity ofprior art initiators. Thus, circuit elements such as the firing switchand the firing control circuitry in the initiator can be assembled fromcircuit elements that are much smaller than those required in prior artinitiators.

[0040] In addition, the present invention provides an ordnance firingsystem with initiators comprising initiator control circuits havingnumerous features described below, any one or more of which may bepresent alone or in combination with any other features disclosedherein.

[0041] This invention provides an ordnance firing system characterizedby novel configurations of initiators, a firing control system and acommunication structure. The novel configurations pertain to thestructure of the initiators to which the control system is connected,the mode for connecting the initiators to the firing control system andone or more modes of operation of the ordnance firing system, i.e.,modes of operation by which the firing control system and initiatorscooperate to operate the effectors with which the initiators areassociated. The communication structure of an ordnance firing system ofthe present invention may include or feature any one or more of: a two-,three- or four-wire communication bus between the control unit and theinitiators; an addressable initiator system in which all the initiatorscan be connected to the same communication bus and the firing controlsystem unit can issue coded signals on the bus addressed to a specificinitiator; the use of inductive coupling between the initiators and thecommunication bus; the use of a multi-voltage level communication systemin which communication signals are carried at a first voltage and armingsignals are provided at a second, higher voltage. Other features mayinclude the use of two-way communication between initiators and thefiring control system unit and the de-centralization of firing controllogic so that the firing control system does not have exclusive controlover whether the initiators function. An initiator for use in aerospacedevices or land vehicles according to this invention may thereforeinclude initiator control circuitry of its own and as a result, theindividual initiators are seen to possess decision-making ability and,for purposes of this invention, are therefore referred to as“intelligent” initiators. To participate in the decision-making process,initiators of this invention may be equipped with sensors or otherdiagnostic circuitry whose condition is checked for satisfactory outputbefore functioning is permitted to occur. Other safety features,described herein, may be present as well.

[0042] A prior art missile equipped with guidance circuitry and ordnancecontrol circuitry in accordance with the prior art is depicted in FIG.6. Missile 110 is shown schematically as comprising guidance and controlcircuitry 117 which includes its own power source 119, a low-powerbattery of size, weight and energy sufficient only for poweringcircuitry 117. Typically, an aerospace control circuit for an aerospacedevice comprises an integrated circuit, e.g., a microcomputer or anASIC, which requires small amounts of power and for which a low-energypower source 119 capable of providing not more than 50 watts istypically provided. In addition, missile 110 comprises ordnancecontroller circuitry 112 and a plurality of initiators 116, 118, 120,122 which are associated with various reactive effectors. Circuitry 112connects to the initiators via separate channel lines, typically witheach initiator on its own line. As indicated above, the initiators arecoupled to effectors which may constitute a variety of different kindsof devices, e.g., separation devices such as exploding bolts, boltcutters, explosive nuts, inflators, actuators, and the like, forcarrying out various functions of the missile in flight, e.g., therelease of stages or strap-on accessories, the deployment of aerodynamicfins, the initiation of an explosive munition, cutters for the releaseof a panel and an inflator for dispelling a payload, e.g., bomblets,through the opening provided by the cut panel, etc. Prior art initiators116, 118, etc., function by the use of a hot bridgewire or other priorart initiating element which consumes a large amount of electricalpower. For this reason, missile 110 carries a high-power energy source115, which may be a chemical or thermal battery or the like capable ofproviding the hundreds of watts needed by each of the initiators. Theseparate power supply is needed because the power requirements forarming and firing the prior art initiators exceeds what can be providedby a power supply normally sufficient for powering guidance and controlcircuitry 117. It will be appreciated that missile 110 of FIG. 6 isrepresentative of various other kinds of aerospace or aeronauticaldevices which may employ an integrated ordnance system in accordancewith this invention.

[0043]FIG. 1A provides a schematic illustration of a missile 10 equippedwith an ordnance firing system in accordance with the present invention.The ordnance firing system comprises a firing control system 12, acommunication bus 14, and a plurality of initiators 16, 18, 20, 22 forreactive effectors on the device. The initiators are connected to thebus 14 and a remote sensor 24 is also connected to bus 14.

[0044] By virtue of the present invention, missile 10 exhibits severalsignificant advantages over prior art missile 110 (FIG. 6). First,initiators 16, 18, 20 and 22 comprise planar, low-energy initiators asdisclosed herein, e.g., SCB initiators, tungsten bridge initiators, etc.These initiators are designed to function reliably and safely and withmuch less power than prior art initiators. As a result, the ordnancefiring system does not need a high-energy power source of the power,size or weight scale of high-energy power source 115 (FIG. 6). Instead,the circuitry which controls the functioning of the initiators ispowered by a low-energy power source 17 (FIG. 1A) which is sufficientfor the arming and firing of the initiators. Low-energy power source 17is the kind of power source normally associated with integrated controlcircuitry and, optionally, the same power source may be used to providepower for the guidance circuitry as well as for the ordnance firingcircuitry. For this reason, in one embodiment of this invention, theordnance firing system need not have its own power supply. Instead, itmay be configured to include a power input junction (e.g., a pin-typejunction) for connection to the power source for the other circuitrywith which it will be used. Such an embodiment of this inventiontherefore simply comprises initiators comprising planar, low-energyinitiator elements, the firing control system circuitry, thecommunication link between the initiators and the firing control systemcircuitry, and an input port for receiving power from the low-energypower source associated with the remainder of the circuitry on theaerospace device. The small energy requirements for a planar, low-energyinitiation element make possible the use of an energy storage device,i.e., firing capacitor, that may be connected to or formed as part ofthe integrated circuit comprising the firing circuitry of the initiator.Due to the low energy consumption of a planar, low-energy initiationelement, upon firing, the firing capacitor may be charged to its ready(“armed”) state by power provided by the low-energy power source.

[0045] Reduction in power consumption may also be realized by using highimpedance initiator firing circuitry. Therefore, in accordance with thepresent invention, the circuitry within initiators 16, 18, etc., mayprovide an input impedance of 1,000 ohms or more, e.g., 1,000 to 10,000ohms. Providing such an unusually high input impedance also providesprotection against accidental initiation resulting from stray signals onbus 14. Optionally, the high input impedance can be attained byisolating the initiator circuitry from the communication bus by the useof resistors.

[0046] As indicated above, missile 10 is merely representative of onetype of aerospace device on which an ordnance firing system inaccordance with the present invention may be employed. Other suchdevices include launch vehicles, which require many of the functionsrequired in missiles. In addition, launch vehicles often requireadditional functions for which the ordnance firing system of thisinvention may be employed. For example, a launch rocket may have arequirement pertaining to stage separation, for which it may benecessary to initiate a plurality of exploding cutters or fasteners suchas exploding bolts, or to initiate one or more frangible joints of thekind described in U.S. Pat. No. 6,125,762 to Fritz et al, dated Oct. 3,2000, the disclosure of which is hereby incorporated herein by referenceas background material. Other functions may pertain to the release ofstructural elements such as covers, the deployment of sub-munitions froma missile and to igniting rocket motors. An ordnance firing system ofthis invention may also be used on satellites, which employ ordnancesystems to control reactive effectors for the deployment of structuressuch as antennae and solar panels. The advantage provided by thisinvention, i.e., use of a low-energy power source, is especiallyimportant in a satellite prior to the deployment of the solar panels. Tothat point, the satellite must function solely on energy provided frombatteries stored thereon. The reduction of weight resulting from the useof the SCB initiators in accordance with the present invention and theuse of a low-energy power source which is significantly smaller andlighter than those which have been used in the prior art reduces theweight of the satellite and therefore the fuel requirements of allstages of the rocket used to place the satellite in orbit. Conversely,for a given rocket configuration, the use of the present inventionpermits, without added cost, the deployment of a satellite with morehardware than was previously possible using prior art ordnance firingsystems.

[0047] Another example of an aerospace device comprising reactiveeffectors for which the ordnance firing system of the present inventionmay be employed is shown in U.S. Pat. No. 5,884,866 to Steinmeyer et al,dated Mar. 23, 1999, which discloses a satellite dispenser for releasinga plurality of satellites into orbit from a launch vehicle. Similarly,the ordnance firing system of this invention may be employed to initiatethe effectors shown in the following patents: U.S. Pat. No. 6,135,391 toVan Woerkom, dated Oct. 24, 2000, which discloses explosively actuatedpin assembly effectors for a retention system for a detachablespacecraft capsule; U.S. Pat. No. 6,016,999 to Simpson et al, dated Jan.25, 2000, which discloses explosive bolt effectors for spacecraftplatforms which are released from a pre-deployment position; U.S. Pat.No. 5,823,469 to Arkhangelsky et al, dated Oct. 20, 1998, whichdiscloses explosive bolt and pyro-push rod effectors for a missilelaunching and orientation system in which the missile comprises anannular body that can be ejected during flight; and U.S. Pat. No.5,529,264 to Bedegrew et al, dated Jun. 25, 1996, which disclosesexplosive bolt effectors for a launch missile system. All of theforegoing patents are incorporated herein by reference as backgroundinformation.

[0048] The assembly of an initiator comprising a planar, low-energyinitiation element for use with effectors on an aerospace device or landvehicle will now be described. A SCB is formed as is known in the priorart, to provide a SCB initiation element on a non-conductive substratefor use in initiator 250 (FIG. 1B). Initiator 250 comprises an outputhousing 252, a body portion comprising sleeve 254 and an input portioncomprising input connector 256. As indicated above, output housing 252is configured to conform to a standard interface commonly used foreffectors in aerospace devices, e.g., it may comprise a fitting inaccordance with a specification known in the aerospace industry asAS4395 (0.375-24 UNJF). As shown in FIG. 1B, such a housing comprises ahex nut portion 252 d and a threaded head portion 252 a for coupling toa threaded effector. Head portion 252 a contains a glass or ceramicinsulator on which a SCB 234 is mounted. The SCB 234 is disposed in arecess in which a reactive output charge 252 b is disposed. The outputcharge is maintained in the recess by a cushion material and arupturable disc 252 c which is welded to housing 252.

[0049] The output charge 252 b may comprise any suitable reactivematerial which, upon functioning of the SCB initiation element, willreact, displace or burst rupture disc 252 c and provide the outputnecessary to initiate the associated effector. In one particularembodiment for producing a pyrotechnic output, output charge 252 b maycomprise a zirconium/potassium perchlorate (ZPP) pyrotechnic mixture. Itwill be understood that other pyrotechnic materials could be used with,or instead of, ZPP, and that an explosive material could be used if anexplosive output is desired. The term “reactive material” as used hereinencompasses both pyrotechnic and explosive materials. Output housing 252also includes a base portion 252 e which is welded to sleeve 254.

[0050] Within sleeve 254 is disposed initiator firing circuitry 254 a,which preferably comprises integrated circuitry. Initiator firingcircuitry 254 a may include communication circuitry and, optionally, astorage capacitor for obtaining and storing energy for firing the SCB.Initiator firing circuitry 254 a communicates with the SCB initiationelement via output lines 254 b, and with the ordnance system firingcontrol circuitry (not shown) by means of four wires connected to fourpins, only two of which are shown, pins 256 a and 256 b, which aresecured to initiator 250 via input connector 256. Pins 256 a and 256 band the other electrical conductor pins may be mounted in a glass plugin input connector 256. Input connector 256 is welded to sleeve 254 atthe end opposite from output housing 252. Input connector 256 ispreferably configured as a standard connector, e.g., it may comprise aconnector in accordance with a specification known in the aerospaceindustry by the designation MIL-C-26482. Typically, output housing 252,sleeve 254 and input connector 256 will all be formed from 304Lstainless steel and the resulting initiator will be hermetically sealedto protect the components therein.

[0051] In various embodiments, input connector 256 may be adapted toinclude as many input pins (2, 3, 4, etc.) as is required by initiatorfiring circuitry 254 a and the ordnance system firing control system(not shown). Likewise, it will be recognized by one of ordinary skill inthe art that initiator 250 may comprise any other suitable couplingmeans in place of, or in addition to, hex nut portion 252 d of theAS4395 fitting in order to secure initiator 250 to its associatedeffector. Such coupling means may include, for example, the features ofa bayonet-style mount, a latch-style mount, etc.

[0052] Referring again to FIG. 1A, another feature of the ordnancefiring system of this invention is the use of a multi-line party bus forestablishing communication between the firing control system circuitryand the various initiators. This feature provides advantagesirrespective of whether an initiation system employs planar, low-energyinitiators and a low-energy power source. According to this feature,initiators 16, 18, 20 and 22 each contain communication circuitry forreceiving and evaluating signals received via communication bus 14 fromfiring control system 12 or, optionally, at least one remote sensor 24.Since all of the initiators are connected to the same communication bus14, they all receive each of the signals issued by firing control system12. However, in accordance with the present invention, initiators 16,18, etc., contain initiator firing circuits that are programmed torecognize an address portion of signals received on communication bus14. The initiator firing circuit is programmed only to respond to thosesignals that contain an address code identified with that initiator. Theaddress code may constitute a specific address unique in the system tothat initiator; it may be a “shared” address also recognized by someother initiators in the system but not all of them, or it may be a“universal” address which all initiators connected to bus 14 recognize.Firing control system 12 and remote sensor 24 are configured to emitsignals that contain the appropriate address codes so that the signalswill be recognized and acted upon by the appropriate initiators.

[0053] As a result of the use of coded signals, initiators 16, 18, etc.,may be connected to shared wires in communication bus 14 and bus 14 maytherefore comprise merely two or three communication wires. A four-wirebus might be used as well, to provide separate wires for arming power,operation power, communication and ground. Similarly, initiators 16, 18,etc., may optionally be configured to generate and emit initiatorsignals onto communication bus 14. Firing control system 12 maybe-designed to receive and interpret initiator signals received via bus14. The signal emitted by an initiator may contain an identifier codethat is unique to the issuing initiator so that the firing controlsystem can distinguish among signals from the various initiators.Accordingly, one feature of the present invention is that firing controlsystem 12 and initiators 16, 18, etc., are configured for two-waycommunication along bus 14. This feature of the invention allows for anordnance firing system in which initiators can provide feedback to thecontrol unit along the bus. The ordnance firing system can be configuredso that, prior to a firing sequence, the firing control system unitissues a query signal to one or more initiators and the initiatorsrespond to indicate their readiness to function.

[0054] One feature of an ordnance firing system according to thisinvention is that the initiators may communicate with the firing controlsystem to indicate their readiness to function before actually beingarmed. This greatly enhances the safety with which such a query can becarried out.

[0055] Optionally, sensors connected to the bus may respond to querysignals on bus 14 with sensor feedback signals. The sensor feedbacksignals may optionally report the result of a self-test in which theinitiator and/or sensor indicates the condition of its internalcircuitry and/or its readiness to function. Likewise, remote sensor 24may be equipped to issue a signal addressed to firing control system 12that reflects a condition that bears on whether one or more of theinitiators in the system should function. The content of the sensorsignal from remote sensor 24 may be used to determine what other signalsshould be emitted by firing control system 12. Internal or externalsensors for use in or with any one of initiators 16, 18, etc., tomeasure any of a variety of parameters may include an accelerationsensor, to sense up to 20 g acceleration or greater, and/or anatmospheric pressure sensor to indicate changes in atmospheric pressureor a rate of atmospheric pressure change. Other factors that might bereported by sensors could include humidity or moisture andelectromagnetic radiation.

[0056] Another advantage associated with the use of a communication busas shown in FIG. 1A and the use of addressable initiators is that such asystem can easily be modified to accommodate any desired number ofinitiators. Prior art ordnance firing systems as represented in FIG. 6require individual wires for each initiator and their firing controlsystems have limited capacity with regard to the number of initiatorsthey can service. To utilize such a system in an aerospace devicerequiring more than the fixed maximum number of initiators, it isnecessary to install a second firing control unit for the additionalinitiators. In contrast, by employing a bus architecture, as manyinitiators as may be desired can be spliced into the bus. The associatedfiring control system is programmable and is easily adapted by one ofordinary skill in the art to control as many initiators as may bedesired to include on the bus.

[0057] Another feature of the present invention is that firing controlsystem 12 and initiators 16, 18, etc., may be configured so thatdifferent types of signals are conveyed at different power levels, e.g.,different voltage levels along bus 14. For example, communicationsignals, e.g., signals from firing control system 12 intended only as aquery to the initiators for readiness, response signals from theinitiators to firing control system 12 indicating their readiness to bearmed, and fire initiation signals from firing control system 12 to theinitiators may occur at a low power level, preferably lower than theno-fire threshold of the initiators. In this way, test and programmingsignals that are not intended themselves to arm and/or initiate theinitiators are carried out at a level that is insufficient to arm and/orinitiate the initiators even if the communication signals are somehowmisinterpreted. Such communication signals may be carried on bus 14 at,e.g., about 7 volts. When the system is ready for arming, the energy forarming the initiators may be provided at a higher level than thecommunication signal level, e.g., at 28 volts. Optionally, the armsignal and communication signal can travel on separate communicationwires in bus 14. Bus 14 may comprise three wires, a power or armingwire, a communication wire and a ground wire, or four wires to permitseparation of the firing system power supply from the arming power wire.The use of bus 14 obviates the need for direct, exclusive point-to-pointhardwire connections between the firing control system and eachinitiator.

[0058] Another feature of the present invention provides that initiators16, 18, etc., need not be hard-wired to bus 14. Instead, they may beconnected to bus 14 via magnetic or inductive couplings. Such couplingsprovide an advantage over hard-wire connections in that the magnetic orinductive coupling inherently acts as a buffer to prevent certain kindsof unwanted signals from flowing between the initiators and the bus. Inaddition, inductive coupling will permit reliable signal transfer in avariety of adverse conditions, e.g., in environments that may be dry,humid, wet, dirty, etc., and through a variety of media: vacuum, gas,liquids, solids, etc. Initiators designed for inductive coupling to bus14 can be designed to be especially resistant to malfunctions induced byelectrostatic discharge and ambient radio frequency signals when theyare not connected to the bus. An inductive coupling will also allow bothcommunication signals and power signals to be multiplexed on the samesignal medium. Optionally, the inductive coupling may be integrated intothe initiator housing.

[0059] As indicated above, one novel feature of the present invention isthat the control over the firing event may reside more in initiators 16,18, etc., than in the prior art. In a system according to the prior art,a firing control system 112 (FIG. 6) issues signals, e.g., a high-powerpulse, forcing the initiators to initiate the effectors, and theinitiators were not equipped to override the firing signal received fromthe control unit. Stated differently, with prior art initiators, asignal from the firing control system unit was sufficient to initiatefiring. In contrast, one aspect of the present invention provides“intelligent” initiators. Intelligent initiators possess initiatorcontrol circuitry having some ability to override a signal from thefiring control system indicating readiness to fire, thus de-centralizingthe firing decision from the firing control system. The firing signalfrom the firing control system then becomes one input or factor takeninto account by the initiator in deciding whether to fire. Other signalsbearing on the decision to fire may be derived from sensors to which theinitiator is responsive.

[0060] Where the ordnance firing system comprises one or more sensors,each sensor may measure a condition which is a condition precedent tofiring, i.e., some or all of the initiators in the ordnance firingsystem may be required to delay firing until the sensor indicates thatthe condition is obtained. For example, in the case of a missile, thesensor may indicate distance from the plane from which the missile isfired and the condition precedent may be a minimum required distancefrom the plane. Optionally, the initiator control circuitry and one ormore initiators may be programmed to postpone function until such asignal is received from the sensor. Therefore, the firing controlcircuitry of the integrated ordnance system may provide only part of theinstructions and impetus required by the initiator to fire. For example,the firing control circuitry may provide a signal indicating readinessto arm the initiator and may provide a low-energy source for arming theinitiator, but the initiator may then wait for input from the sensorbefore functioning. This allows the system to respond to environmentalconditions that may vary after the firing control system has determinedthat conditions for firing are imminent. Such sensors may include theremote sensor 24 connected to bus 14. In other embodiments of theinvention, however, the sensor may be associated exclusively with theinitiator making the firing “decision”. For example, there is anexternal sensor 18 a associated with and directly connected to initiator18. Either or both of sensor 18 a and sensor 24 may sense, for example,any one or more environmental variables pertinent to the function of theinitiator or the ordnance system as a whole.

[0061] In various applications, external factors describing the motionof the initiator or a device on which the initiator is mounted (e.g., amortar shell) may be required to determine the proper conditions forfiring. Sensors that indicate acceleration, roll rate, pitch, yaw,velocity, distance, altitude, attitude, temperature, hydraulic oratmospheric pressure, etc., may provide information that is significantto the proper functioning of the initiator 18. Initiator 18 may thencomprise initiator control circuitry that will, upon receipt of a firingsignal from firing control system 12, receive and evaluate the output ofsensor 18 a and may then function only if it determines that sensor 18 aindicates favorable conditions. Similarly, initiator 22 is responsivenot only to signals from firing control system 12 but also to aninternal sensor 22 a which may sense conditions inside the initiatorshell. Such internal conditions may include the condition of the firingcircuitry of initiator 22, the condition of the output charge ofinitiator 22, etc. Other relevant internal conditions that might bereported by sensor 22 a include temperature, voltages, frequencies,current draw, initiation element continuity, etc. If a firing signal isreceived from firing control system 12 but the requisite signal is notreceived from the sensor 22 a, initiator 22 may optionally be programmedto postpone firing despite the firing signal from firing control system12. Sensor 22 a may thus provide a built-in test function formanufacturing quality as well as field reliability.

[0062] According to another aspect of the present invention, thedecision to arm and/or initiate one or more initiators may be based on atime-phased sequence of one or more sensor signals. In other words, theordnance firing system (i.e., the firing control system and/or one ormore intelligent initiators) may respond to a temporal characteristic orprofile of a sensor signal and thus to a temporal characteristic of theinternal or external condition associated with that sensor, rather thanto a single, instantaneous and possibly artificial or accidental valueof the signal or of the condition. For example, rather than makinginitiation dependent upon the receipt of a sensor signal that indicatesattainment of acceleration of 30 g or more (either as the sole conditionof initiation or as one of a combination of conditions), the system maybe programmed to respond to a signal having a predetermined temporalprofile which indicates that acceleration of 30 g or more is attainedand is followed by at least 3 seconds of acceleration of at least 3 g.As another example, initiation may depend upon receiving signals thatindicate that a pressure altitude of less than 500 feet is attainedafter a pressure altitude of at least 3000 feet is registered for atleast 10 minutes. Such temporal analyses of sensor signals permitgreater specificity in defining the conditions under which initiation isdesired than decision processes that respond merely to the instantaneousmagnitude of a sensor signal without regard to its temporal profile. Forexample, the temporal acceleration analysis described above permits thesystem to distinguish between the air-borne deployment of a munition andthe inadvertent dropping of the munition from a loading fixture onto awork site floor. Optionally, initiation may be associated with acombination of temporal characteristics of two or more sensor signals,or a combination of one or more temporal sensor signal profiles with oneor more instantaneous sensor signal values.

[0063] Optionally, the output signal from sensor 18 a or sensor 22 a maybe delivered to bus 14 as data for use by other initiators or by thefiring control system 12. The two-way communication between the firingcontrol system 12 and a specific initiator along bus 14 as describedabove may include signals from a sensor specifically associated with aparticular initiator as sensor 22 a is specifically associated withinitiator 22. The sensor signal, having been conveyed via bus 14, mayoptionally be read as input data by other initiators as well as by thefiring control system 12. The use of a sensor closely associated with aninitiator as described above results in improved reaction time for theinitiator and the system as a whole because the data required todetermine whether the initiator is ready to function is derived from anearby source. Also, the size and weight of such sensors are smallerthan that of sensors in prior art systems.

[0064] In one optional embodiment of the invention, any one or more ofinitiators 16, 18, etc., may be “self-arming”. Rather than dependingupon the receipt of an arming signal from firing control system 12, aself-arming initiator in accordance with the present invention mayrespond to signals received from internal or external sensors associatedtherewith, and/or signals received via bus 14 from firing control system12, one or more of sensor 18 a, sensor 22 a and sensor 24, etc., anddetermine whether such signals indicate a predetermined condition atwhich the initiator should arm itself. (Arming generally refers to thecharging of a firing capacitor whose subsequent discharge through thesemiconductor bridge will initiate the device). The energy for armingthe initiator may be supplied from a battery that serves only to arm theinitiators, or it may be drawn from firing control system 12, based onpower drawn from the power source for firing control system 12.Alternatively, the initiator control circuitry may arm the initiatorsolely in response to an arm command issued by the firing controlsystem. In another embodiment, the firing control system may be able toprovide power for arming the initiator directly, without having tocontrol the operation of an arming switch in the initiator.

[0065] It will be evident in view of the discussion above that anordnance firing system in accordance with the present invention thatcomprises intelligent initiators differs from blasting-type initiationsystems because in a typical mining blast, the number and sequence ofinitiations is predetermined. The use of “intelligent initiators” thatrely on sensors as described herein to determine whether or not it isappropriate to arm and/or to fire the associated effector provides asystem in which an on-going assessment of the environment can determinewhich initiators function, even after the initial firing of the firstreactive effectors. In blasting operations, the arming decision is madeat a central control unit and once the blast has started, the systemgenerally does not provide any way for it to vary or alter in acontrolled, calculated manner the order or sequence in which detonatorsare fired.

[0066] In FIG. 1C, an ordnance firing system 310 in accordance withanother embodiment of the invention is shown. System 310 comprises afiring control circuit 312 which communicates with initiators 16, 18, 20and 22 via communication bus 14 in the same way that the firing andguidance circuitry 12 (FIG. 1A) of rocket 10 communicates withcorresponding structures shown therein. In the embodiment of FIG. 1C,however, firing control circuit 312 contains no power source of its own.Instead, it both communicates and draws power from the guidance andcontrol circuitry 313, which shares power from the low-energy powersource therein. Firing control circuit 312 is equipped with an inputport 314 for receiving communication signals and power from guidance andcontrol circuit 313.

[0067] In an optional embodiment of an integrated ordnance system inaccordance with the present invention, the firing control system and atleast one initiator are configured to provide a time-phased arming. Inaccordance with this feature of the system, which will be describedherein with reference to FIG. 2, a communication bus 14′ and firingcontrol system (not shown) are configured to provide external armingpower on one line and an arm command communication signal on anotherline. The external arming power is provided in order to arm initiator 16a by charging firing capacitor 26 with energy sufficient to initiate thesemiconductor bridge (not shown) in initiator 16 a. The external powermust pass through arming switch 28 to charge firing capacitor 26. Armingswitch 28 is designed to close only for a fraction of the time requiredto charge capacitor 26 from bus 14′. Arming switch 28 is thereforereferred to as a “momentary switch”. Arming switch 28 is under thecontrol of arming switch control circuit 30 which is part of theinitiator control circuitry disposed within initiator 16 a. The armcommand received via communication bus 14′ is conveyed to arming switchcontrol circuit 30. In accordance with this aspect of the invention,arming switch control 30 will only close arming switch 28 once for eacharm command received so that firing capacitor 26 cannot progress from afully discharged condition to a charge sufficient to initiate thesemiconductor bridge during a single arming interval. Rather, eacharming interval provides only a partial charge for firing capacitor 26.Accordingly, a series of arming signals is required, and a full chargecan only be attained in a stepwise fashion, as depicted in FIG. 3.Referring again to FIG. 2, firing capacitor 26 is connected in parallelwith a bleed resistor 32 which tends to bleed off the partial chargesimposed on firing capacitor 26. Accordingly, in order to fully chargefiring capacitor 26, a series of arming intervals during which armingswitch 28 is closed must occur with sufficient duration and frequency toovercome the dissipative function of bleed resistor 32. The armingswitch control circuit 30 closes and opens arming switch 28 once andonly once for each arm command. Once armed, i.e., once firing capacitor26 is charged sufficiently to initiate the initiation element in theinitiator, the periodic arm commands must continue in order to maintainthe sufficient charge in capacitor 26. In effect, the configuration ofcircuit elements shown in FIG. 2 provides a safety feature in whichinitiator 16 a can only be armed for firing if arm commands aregenerated from the control unit (not shown in FIG. 2) at a frequencydetermined by the requirements of the circuitry in initiator 16 a. Thespecific requirements for arming initiator 16 a make unintended armingand firing by virtue of stray electromagnetic signals or as the resultof malfunction of the control unit highly unlikely.

[0068]FIG. 4 provides a schematic diagram of an initiator controlcircuit with separate connection leads for input power and communicationsignals from the communication bus according to a particular embodimentof this invention. The conditioning circuit 34 of initiator 16 bconverts the input power to a direct current voltage that is suited foruse by the remainder of the initiator circuitry. Optionally,conditioning circuit 34 could have a high impedance to externalpotentials as an added safety feature against inadvertent initiationcaused by stray signals or noise as may be induced by ambient radiofrequency signals. The input power received by conditioning circuit 34may be at various levels which may be used as follows: at 0 to 5 volts,no significant reaction or response is generated in initiator 16 b. Asignal between 5 and 20 volts may be used for communication, to closeswitches for arming and firing, to obtain information in response toself-diagnostic sensors (not shown) in initiator 16 b, etc., but signalsat this voltage level are lower than the no-fire level of the initiator.This allows for communication with the added safety feature of usingsignals which, even if misinterpreted as a firing signal, haveinsufficient magnitude to arm and fire the device. Signals at greaterthan 20 volts DC can be used for communication, to operate arming andfiring switches, to obtain status information and to fire the initiator.Voltage regulator 36 takes the conditioned input power and regulates itto a nominal voltage, typically 3.3 or 5 volts DC for use by theprocessing/status circuit 38.

[0069] In the embodiment of FIG. 4, initiator 16 b preferablycommunicates with a firing control system (not shown) through acommunication bus, through a hardwire link, inductive coupled link, awireless link, an optical link, etc. Alternatively, communication andpower signals may be delivered via a direct wire connection rather thanover a bus.

[0070] The processing/status circuit 38 interprets commands sent fromthe firing control system unit and performs the arming, firing,self-test, etc., functions and, when appropriate, issues a responsesignal to the firing control system or, along a bus, to otherinitiators. Arming switch 28 applies firing voltage to the firingcircuitry 40. Initiator firing circuitry 40 will contain the necessaryelectronic, mechanical, optical, etc., components to force the initiatorto function and will include, for example, a source of initiation energysuch as a firing capacitor (not shown), a firing switch (not shown),etc. The initiation element 42 may be a semiconductor bridge or otherlow-energy, e.g., planar, initiation element, or a prior art elementsuch as a hot bridgewire, exploding bridgewire, etc.

[0071] There is shown in FIG. 5 an initiator 16 c in accordance with aspecific embodiment of the present invention. Initiator 16 c is joinedto a party line bus 14. Signals received from the firing control systemvia bus 14 pass through several buffer devices including common mode EMI(electro-magnetic interference) filter 44, high impedance isolators 46and over-voltage clamp 48. EMI filter 44 provides protection againstsusceptibility to random electro-magnetic signals that may beinadvertently conveyed along bus 14. Impedance isolators 46 limit theenergy that can be received from bus 14 for use by the remainder of theinitiator circuit.

[0072] A signal that meets the requirements of the buffer provided byEMI filter 44, isolators 46 and clamp 48 is then conveyed to armingswitch 28, power supply circuit 50 and data communication circuit 52. Aninitiator control circuit 54 receives input from data communicationcircuit 52 and power supply 50 as well as status information from energystorage (e.g., capacitor) 26 and the initiation element, e.g.,semiconductor bridge 42 a. When the proper input signals are receivedfrom these sources, initiator control circuit 54 may issue an armingsignal. In the illustrated embodiment, the arming signal is received bya logic gate 54 a which also receives input from an internal sensor 56.If the output of internal sensor 56 is appropriate for the operation ofarming switch 28, logic gate 54 a may convey the control arming signalfrom control circuit 54 to arming switch 28, through which a chargingvoltage may be applied to the energy storage device, i.e., a firingcapacitor 26. Optionally, charging may occur in a set fashion asdescribed in connection with FIGS. 2 and 3. When the initiating elementis a semiconductor bridge, the energy requirement for initiation issubstantially smaller than in prior art devices, so firing capacitor 26,which may typically be sized to release only 5 millijoules, may beemployed for a 1-ohm SCB, obviating the need for a battery as would berequired by prior art devices. When appropriate signals are received,control circuit 54 may issue a control firing signal for firing switch58. In the illustrated embodiment, an optional logic gate 54 b comparesthe control firing signal to the output of an environmental sensor 18 aand only conveys the control firing signal to the firing switch when theenvironmental sensor 18 a indicates that conditions are appropriate forfiring. The closure of firing switch 58 permits the discharge of firingcapacitor 26 through the semiconductor bridge 42 a or other initiationelement, thus initiating the device.

[0073] In addition to providing input to logic gates 54 a and 54 b,internal sensor 56 and external sensor 18 a may provide signals directlyto initiator control circuit 54 and/or data communication circuit 52 sothat initiator 16 c can perform a self-test for readiness prior to thereceipt of an arming or firing signal from party line bus 14.Optionally, the self test can be performed in response to a query signalreceived from bus 14 and the results may be reported in a responsesignal emitted along bus 14.

[0074] As indicated above, the present invention also finds utility inland vehicles, e.g., in automobiles, trucks, buses, trains, etc., forpurposes that may include initiating the inflation of air bag safetysystems. In such applications, the ordnance firing system includessensors which signal to the firing control system circuitry the locationof an impact on the vehicle, the occurrence of a roll-over, or otherconditions that bear on which of the effectors, i.e., air bag inflators,should be initiated.

[0075] In the case of a land vehicle in which an ordnance firing systemis used for initiating a safety system, e.g., air bag(s) and belttensioners, a condition precedent to firing may be the sensing of animpact. Such safety systems are known and are disclosed in, e.g., U.S.Pat. No. 5,829,841 and U.S. Pat. No. 5,829,784, both of which areincorporated herein by reference as background information. The initialsensing of an impact may result in the issuance of a command to arm allthe initiators in the system, but selected initiators might beprogrammed only to fire when associated sensors indicate an impact inthe area of the initiator. Thus, the ordnance system can be programmedonly to inflate a driver's side air bag when impact on the driver's sideof vehicle is sensed. In contrast, the ordnance system may be programmedto initiate other effectors, e.g., seat belt tensioners, in response toa much broader range of sensor inputs, e.g., in response to theindication by any sensor of a vehicle impact. Thus, the ordnance firingsystem can be programmed so that some initiators are responsive to moresensor signals than others. In an alternative embodiment, certain sensoroutput signals may constitute conditions precedent to arming one or moreof the initiators and either the firing control system or the initiatorcontrol circuitry may be responsive to the sensor so that the initiatoris not armed until the sensor generates the appropriate signal.

[0076] The invention described herein provides initiators and anintegrated ordnance system in which the initiators may have a high inputimpedance which, in turn, provides simple EMI control, protectionagainst inadvertent initiation caused by transient signals and efficientenergy storage. A variety of coupling arrangements may be used toestablish a link between an initiator and a communication bus, includingmagnetic coupling. MEMS (micro-electronic machines) technology mayoptionally be incorporated for enhanced safety.

[0077] While the invention has been described in detail with respect toparticular embodiments thereof, it will be apparent that upon a readingand understanding of the foregoing, numerous alterations to thedescribed embodiments will occur to those skilled in the art and it isintended to include such alterations within the scope of the appendedclaims.

What is claimed is:
 1. In an aerospace device comprising a plurality ofreactive effectors, the improvement comprising a plurality of initiatorscomprising planar, low-energy initiation elements operatively associatedwith the effectors for initiating the same.
 2. The device of claim 1comprising a low-energy power source connected to the initiators toprovide power for arming the initiators.
 3. The device of claim 1, theimprovement further comprising: firing control system circuitryconnected to the initiators for controlling the firing of the pluralityof initiators; and a low-energy power source for arming the initiators.4. The device of claim 1, claim 2 or claim 3 comprising a commoncommunication bus connecting the initiators to the control circuitry. 5.The device of claim 1, claim 2 or claim 3 wherein the device comprisesone of a missile and a launch vehicle.
 6. The device of claim 5comprising effectors selected from the group consisting of explodingbolts, bolt cutters, motor igniters, release fairings and destructcharges.
 7. In an aerospace device comprising a plurality of reactiveeffectors, the improvement comprising: a plurality of initiatorsassociated with the effectors; a firing control system in communicationwith the initiators; and at least one sensor, on the device, for sensinga condition precedent to arming or firing at least one initiator;wherein at least one initiator is in communication with the sensor andthat is responsive to the sensor and to the firing circuitry forinitiating its associated effector upon receipt of proper signals fromboth the firing circuitry and the sensor.
 8. The device of claim 7comprising a common bus through which the initiators are linked to thefiring circuitry.
 9. The device of claim 7 wherein the sensor isconnected to the bus.
 10. The device of claim 7 wherein the sensor isconnected to the initiator responsive to it.
 11. The device of claim 7wherein at least one initiator is programmed to self-arm or initiatebased on a signal received from the sensor.
 12. A method for firing aninitiator for a reactive effector in an aerospace device or land vehiclecomprising at least one sensor for a condition precedent to firing theinitiator, the method comprising: taking a time-phased reading of thesensor and comparing the reading to a predetermined temporal profile,and firing the initiator when the reading correlates to thepredetermined profile.
 13. In a land vehicle comprising a plurality ofreactive effectors, the improvement comprising initiators comprisingplanar, low-energy initiation elements for initiating the effectors. 14.The vehicle of claim 13 comprising a low-energy power source connectedto the initiators to provide power for arming the initiators.
 15. Thevehicle of claim 13, the improvement further comprising: firing controlsystem circuitry connected to the initiators for controlling the firingof the plurality of initiators for the effectors; and a low-energy powersource for arming the initiators.
 16. The vehicle of claim 13, claim 14or claim 15 comprising a common communication bus connecting theinitiators to the control circuitry.
 17. The vehicle of claim 13, claim14 or claim 15 wherein the effectors comprise air bag inflators.
 18. Ina land vehicle comprising a plurality of reactive effectors, theimprovement comprising: a plurality of initiators associated with theeffectors; a firing control system in communication with the initiators;and at least one sensor, on the device, for sensing a conditionprecedent to arming or firing at least one initiator; wherein at leastone initiator is in communication with the sensor and that is responsiveto the sensor and to the firing circuitry for initiating its associatedeffector upon receipt of proper signals from both the firing circuitryand the sensor.
 19. The vehicle of claim 18 comprising a common busthrough which the initiators are linked to the firing circuitry.
 20. Thevehicle of claim 18 wherein the sensor is connected to the bus.
 21. Thevehicle of claim 18 wherein the sensor is connected to the initiatorresponsive to it.
 22. The vehicle of claim 18 wherein at least oneinitiator is programmed to self-arm or initiate based on a signalreceived from the sensor.